Surface-modified, doped, pyrogenically produced oxides

ABSTRACT

Surface-modified, doped, pyrogenically produced oxides surface-modified with one or several compounds from the following groups:
     a) Organosilanes of the type (RO) 3 Si(C n H 2n+1 ), (RO) 3 Si(C n H 2n−1 )   b) R′ x (RO) y Si(C n H 2n+1 ), (RO) 3 Si(C n H 2n+1 )   c) X 3 Si(C n H 2n+1 ), X 3 Si(C n H 2n−1 )   d) X 2 (R′)Si(C n H 2n+1 ), X 2 (R′)Si(C n H 2n−1 )   e) X(R′) 2 Si(C n H 2n+1 ), X(R′) 2 Si(C n H 2n−1 )   f) (RO) 3 Si(CH 2 ) m —R′,   g) (R″) x (RO) y Si(CH 2 ) m —R′,   h) X 3 Si(CH 2 ) m —R′,   i) (R)X 2 Si(CH 2 ) m —R′,   j) (R) 2 XSi(CH 2 ) m —R′,   k) Silazanes of the type   

     
       
         
         
             
             
         
       
         
         l) Cyclic polysiloxanes, 
         m) Polysiloxanes or silicone oils.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a surface-modified, doped, pyrogenicallyproduced oxides, a method of their production and their use.

2. Description of Related Art

Pyrogenically produced oxides doped by aerosol are known, e.g., DE 19650 500 A1.

SUMMARY OF THE INVENTION

The invention has as subject matter surface-modified, pyrogenicallyproduced oxides doped by aerosol. The surface-modified, pyrogenicallyproduced oxides doped by aerosol can preferably be characterized in thatthe oxides are from the group SiO₂, Al₂O₃, TiO₂, B₂O₃, ZrO₂, In₂O₃, ZnO,Fe₂O₃, Nb₂O₅, V₂O₅, WO₃, SnO₂, GeO₂.

The surface modification can take place with one or more compounds fromthe following groups:

a) Organosilanes of the type (RO)₃Si(C_(n)H_(2n+1)) and(RO)₃Si(C_(n)H_(2n−1))

R=alkyl, such as, e.g., methyl-, ethyl-, n-propyl-, i-propyl-, butyl-

n=1-20

b) Organosilanes of the type R′_(x)(RO)_(y)Si(C_(n)H_(2n+1)) and(RO)₃Si(C_(n)H_(2n+1))

R=alkyl, such as, e.g., methyl-, ethyl-, n-propyl-, i-propyl-, butyl-

R′=alkyl, such as, e.g., methyl-, ethyl-, n-propyl-, i-propyl-, butyl-

R′=cycloalkyl

N=1-20

x+y=3

x=1, 2

y=1, 2

c) Halogen organosilanes of the type X₃Si(C_(n)H_(2n+1)) andX₃Si(C_(n)H_(2n−1))

X═Cl, Br

n=1-20

d) Halogen organosilanes of the type X₂(R′)Si(C_(n)H_(2n+1)) and

X₂(R′)Si(C_(n)H_(2n−1))

X═Cl, Br

R′=alkyl, such as, e.g., methyl-, ethyl-, n-propyl-, i-propyl-, butyl-

R′=cycloalkyl

n=1-20

e) Halogen organosilanes of the type X(R′)₂Si(C_(n)H_(2n+1)) and

X(R′)₂Si(C_(n)H_(2n−1))

X═Cl, Br

R′=alkyl, such as, e.g., methyl-, ethyl-

R′=cycloalkyl

n-propyl-, i-propyl-, butyl-

n=1-20

f) Organosilanes of the type (RO)₃Si(CH₂)_(m)—R′

R=alkyl, such as methyl-, ethyl-, propyl-

m=0.1-20

R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)

-   -   —C₄F₉, OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂    -   —NH₂, ═N₃, —SCN, —CH═CH₂, —NH—CH₂—CH₂—NH₂,    -   —N—(CH₂—CH₂—CH₂NH₂)₂    -   —OOC(CH₃)c=CH₂    -   —OCH₂—CH(O)CH₂    -   —NH—CO—N—CO— (CH₂)₅    -   —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃ Si(or)₃    -   —S_(x)—(CH₂)₃Si(OR)₃    -   —SH    -   —NR′R″R′″(R′=alkyl, aryl; R″═H, alkyl, aryl; R′″═H,    -   alkyl, aryl, benzyl, C₂H₄NR″″R′″″ with R″″=A, alkyl and    -   R′″″═H, alkyl        g) Organosilanes of the type (R″)_(x)(RO)_(y)Si(CH₂)_(m)—R′

$\begin{matrix}{R^{''} = {alkyl}} \\{= {cycloalkyl}}\end{matrix}$ x + y = 2 x = 1, 2 y = 1, 2 m = 0.1  to  20

R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)

-   -   —C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂    -   —NH₂, —N₃, SCN, —CH═CH₂, —NH—CH₂—CH₂—NH₂,    -   —N—(CH₂—CH₂—NH₂)₂    -   —OOC(CH₃)C═CH₂    -   —OCH₂—CH(O)CH₂    -   —NH—CO—N—CO—(CH₂)₅    -   —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃    -   —S_(x)—(CH₂)₃Si(OR)₃    -   —SH—NR′R″R′″(R′=alkyl, aryl; R″═H,    -   alkyl, aryl; R′″═H, alkyl, aryl, benzyl,        -   C₂H₄NR″″R′″″ with R″″=A, alkyl and R′″″═H, alkyl)            h) Halogen organosilanes of the type X₃Si(CH₂)_(m)—R′

X═Cl, Br

m=0, 1-20

R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)

-   -   —C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂    -   —NH₂, —N₃, —SCN, —CH═CH₂, —NH—CH₂—CH₂—NH₂,    -   —N—(CH₂—CH₂—NH₂)₂    -   —OOC(CH₃)C═CH₂    -   —OCH₂—CH(O)CH₂    -   —NH—CO—N—CO—(CH₂)₅    -   —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃    -   —S_(x)—(CH₂)₃Si(OR)₃    -   —SH        i) Halogen organosilanes of the type (R)X₂Si(CH₂)_(m)—R′    -   X═Cl, Br    -   R=alkyl, such as methyl-, ethyl-, propyl-    -   m=0, 1-20    -   R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)    -   —C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂    -   —NH₂, —N₃, SCN, —CH═CH₂, —NH—CH₂—CH₂—NH₂,    -   —N—(CH₂—CH₂—NH₂)₂    -   —OOC(CH₃)C═CH₂    -   —OCH₂—CH(O)CH₂    -   —NH—CO—N—CO—(CH₂)₅    -   —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃,    -   in which R=methyl-, ethyl-, propyl-, butyl-    -   —S_(x)—(CH₂)₃Si(OR)₃, in which R can=methyl-, ethyl-, propyl-    -   butyl-    -   —SH        (j) Halogen organosilanes of the type (R)₂XSi(CH₂)_(m)—R′    -   X═Cl, Br    -   R=alkyl    -   m=0, 1-20    -   R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)    -   —C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂    -   —NH₂, —N₃, SCN, —CH═CH₂, —NH—CH₂—CH₂—NH₂,    -   —N—(CH₂—CH₂—NH₂)₂    -   —OOC(CH₃)C═CH₂    -   —OCH₂—CH(O)CH₂    -   —NH—C—N—CO—(CH₂)₅    -   —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃    -   —S_(x)—(CH₂)₃Si(OR)₃    -   —SH        (k) Silazanes of the type

R=alkylR′=alkyl, vinyl(l) Cyclic polysiloxanes of the type D 3, D 4, D 5, in which D 3, D 4and D 5 denote cyclic polysiloxanes with 3, 4 or 5 units of the type—O—Si(CH₃)₂, e.g. octamethylcyclotetrasiloxane=D4

m) Polysiloxanes or silicone oils of the type

-   R=alkyl, such as C_(n)H_(2n+1), in which n=1 to 20, aryl, such as    phenyl- and substituted phenyl groups, (CH₂)_(n)—NH₂, H-   R=alkyl, such as C_(n)H_(2n+1), in which n=1 to 20, aryl, such as    phenyl- and substituted phenyl groups, (CH₂)_(n)—NH₂, H-   R=alkyl, such as C_(n)H_(2n+1), in which n=1 to 20, aryl, such as    phenyl- and substituted phenyl groups, (CH₂)_(n)—NH₂, H-   R′″=alkyl, such as C_(n)H_(2n+1), in which n=1 to 20, aryl, such as    phenyl- and substituted phenyl groups, (CH₂)_(n)—NH₂, H

Further subject matter of the invention is constituted by a method ofproducing the surface-modified, pyrogenically produced oxides doped byaerosol and in accordance with the invention, characterized in thatpyrogenically produced oxides doped by aerosol are placed in a suitablemixing container, the pyrogenically produced oxides doped by aerosol aresprayed under intensive mixing, optionally with water and/or acid atfirst and subsequently with the surface-modification reagent or amixture of several surface-modification reagents, optionally re-mixed 15to 30 minutes and are subsequently tempered at a temperature of 100 to400° C. for a period of 1 to 6 hours.

The water used can be acidified with an acid, e.g. hydrochloric acid, upto a pH of 7 to 1. The surface-modification reagent used can bedissolved in a suitable solvent such as, e.g., ethanol. The mixingand/or the tempering can be carried out in an atmosphere of protectivegas such as, e.g., nitrogen.

Further subject matter of the invention includes a production method forsurface-modified, pyrogenically produced oxides doped by aerosol wherethe pyrogenically produced oxide starting material is mixed ashomogeneously as possible with organohalosilanes under conditions, whereoxygen is excluded, followed by a step where the mixture is heated withslight amounts of water vapor and optionally, in a continuous stream ofinert gas in a treatment chamber designed as an upright tubular oven attemperatures of 200 to 800° C., preferably 400 to 600° C., the solid andgaseous reaction products are then separated from each other and thesolid products deacidified again if necessary and dried.

The pyrogenically produced oxides doped by aerosol can be doped,pyrogenically produced oxides of metals and/or metalloids in which thebase components are oxides of metals and/or metalloids producedpyrogenically by flame hydrolysis that are doped with at least a dopingcomponent of 0.00001 to 20% by wt., the doping amount can be preferablyin a range of 1 to 10,000 ppm and the doping component is a metalloidand/or metal or a metalloid salt and/or metal salt or an oxide of ametal and/or metalloids and the BET surface of the doped oxides isbetween 5 and 600 m²/g.

They can be produced in that an aerosol is fed into a flame such as isused to produce pyrogenic oxides by flame hydrolysis in a known manner,this aerosol is homogeneously mixed before the reaction with the gaseousmixture of the flame oxidation or flame hydrolysis, the aerosol/gaseousmixture is allowed to react in a flame and the doped, pyrogenicallyproduced oxides that arise are separated in a known manner from the gasflow, that a saline solution or suspension containing the component ofthe substance to be doped, which can be a metal salt of metalloid saltof mixtures of both or a suspension of an insoluble metal compound ormetalloid compound, serves as initial product and that the aerosol isproduced by atomization by means of a two-fluid nozzle or by an aerosolgenerator preferably in accordance with the ultrasonic method or by someother type of aerosol generation. Such a method is shown in DE 196 50500 A1.

The aerosol can be supplied in a preferred embodiment of the inventionby a device like the one shown in FIG. 1. The lines for the supply ofgas and aerosol can be exchanged with one another.

In a further embodiment the aerosol can be supplied by an annular nozzlearranged at any desired angle, preferably vertically to the main gasflow.

The metalloids/metals aluminum, niobium, titanium, tungsten, germanium,boron, indium, iron, vanadium, tungsten, zinc and/or silicon can be usedas base component.

Metals and/or metalloids and their compounds, in as far as they can bedissolved or suspended in a liquid solution, can be used as dopingcomponent. In a preferred embodiment compounds of transitional metalsand/or noble metals can be used.

For example, cerium and potassium salts can be used as dopingcomponents.

The method of flame hydrolysis for producing pyrogenic oxides is knownfrom Ullmanns Enzylkopädie der technischen Chemie, 4^(th) edition,volume 21, page 464.

As a result of the fine distribution of the doping component in theaerosol as well as the high temperatures (1,000 to 2,400° C.) in thesubsequent flame hydrolysis in which the doping components are, if needbe, further comminuted and/or melted, the doping medium is present infinely divided form in the gaseous phase during the genesis of thepyrogenic oxide so that a homogeneous inclusion of the doping componentinto the pyrogenically produced oxide is possible. However, theattainment of a homogeneous distribution of doping component is possibleby means of a suitable selection of the initial salts and the type ofprocess.

It is possible with the method of the invention to dope all known,pyrogenically produced oxides (e.g., SiO₂, TiO₂, Al₂O₃, B₂O₃, ZnO,In₂O₃, ZrO₂, Fe₂O₃, GeO₂, V₂O₅, SnO₂, WO₃, Nb₂O₅) with other metaloxides or metalloid oxides or their mixtures.

The aggregate structure or agglomerate structure of the pyrogenic oxidecan be influenced by selecting suitable doping components. Moreover, thepH of the pyrogenic oxide can be influenced.

Catalytically active substances (e.g., cerium or noble metals) that canbe used as doping component can, if desired, be distributed almosthomogeneously in the pyrogenically produced oxide.

Even the phase transition of pyrogenically produced oxides, e.g., fromrutile to anatase in the pyrogenically produced titanium oxide, can beinfluenced by doping.

In one embodiment of the invention a pyrogenically produced silicic aciddoped by aerosol with aluminum oxide can be used in which silicic acidthe base component is a silicic acid pyrogenically produced in themanner of flame oxidation, or, preferably, of flame hydrolysis that isdoped with a doping component of 1×10⁻⁴ and up to 20% by wt., the dopingamount is preferably in a range of 1 to 10,000 ppm and the dopingcomponent is a salt or a salt mixture of aluminum or a suspension of analuminum compound or of metallic aluminum or mixtures thereof with theBET surface of the doped oxide between 5 and 600 m²/g, preferably in arange between 40 and 100 m²/g.

The silicic acid can have a DBP number of below 100 g/100 g.

The pyrogenically produced silicic acids doped by aerosol with aluminumoxide can be produced in that an aerosol in fed into a flame such as isused for the pyrogenic production of silicic acids in the manner offlame oxidation or, preferably flame hydrolysis, the aerosol ishomogeneously mixed before the reaction with the gaseous mixture of theflame oxidation or flame hydrolysis, then the aerosol/gaseous mixture isallowed to react in the flame and the pyrogenically produced silicicacids doped with aluminum oxide are separated from the gas current in aknown manner, that an aqueous solution is used to produce the aerosolthat contains salts or saline mixtures of aluminum or the metal itselfin dissolved or suspended form or mixtures thereof, and that the aerosolis produced by atomization by means of a two-fluid nozzle or some othertype of aerosol generation, preferably by an aerosol generator inaccordance with ultrasonic atomization.

The following are used by way of example as salts: AlCl₃, Al₂(SO₄)₃,Al(NO₃)₃.

Further subject matter of the invention is the use of the pyrogenicallyproduced, surface-modified and doped oxides in accordance with theinvention as

-   -   Improvement of the surface quality in coating systems,    -   Reinforcing filler in silicon rubber, rubber and resins,    -   Charge stabilizer and free-flow agent in toner powder    -   Free-flow agent    -   Antiblocking agent, e.g., in foils    -   UV blocker, e.g., in cosmetics    -   Thickening agent, e.g., in paints and other coating systems,    -   Thickening agent, e.g., in resins such as polyester.

As a result of the surface modification the products in accordance withthe invention can be worked in more rapidly and in a higherconcentration into organic systems such as, e.g., polyester resin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the burner arrangement used in the examples.

DETAILED DESCRIPTION OF THE INVENTION Examples

The burner arrangement used in examples 1 to 5 is schematically shown inFIG. 1.

According to FIG. 1 the core piece of the apparatus is burner 1 with aknown construction such as is usually used to produce pyrogenic oxides.Burner 1 consists of central tube 2 that empties into nozzle 3 fromwhich the main gas current flows into the burner chamber and burns offthere. The inner nozzle is surrounded by annular nozzle 4 (jacketnozzle), from which ring hydrogen or secondary hydrogen flows in orderto prevent cakings.

Axial tube 5, that terminates a few centimeters before nozzle 3 ofcentral tube 2, is located in the central tube. The aerosol is fed intoaxial tube 5 and the aerosol gas current of axial tube 5 ishomogeneously mixed with the gas current of central tube 2 in the laststretch of central tube 2. The aerosol is produced in aerosol generator6 (ultrasonic atomizer). An aqueous saline solution containing the metalor metalloid to be doped as salt in dissolved or dispersed/suspendedform is used as aerosol educt. The aerosol generated by aerosolgenerator 6 is conducted by a carrier gas current through heating zone 7where the water evaporates and small saline crystals remain in finelydistributed form in the gaseous phase. Such a device is shown in DE 19650 500 A1.

Example 1 Doping with Cerium

4.44 kg/h SiCl₄ are evaporated at approximately 130° C. and introducedinto the central tube of the burner. In addition, 3 Nm³/h primaryhydrogen and 8.0 Nm³/h air are fed into the central tube. The gaseousmixture flows out of the inner nozzle of the burner and burns into theburner chamber and the subsequent, water-cooled flame tube. In order toavoid cakings on the nozzles 0.5 Nm³/h jacket hydrogen or secondaryhydrogen is fed into the jacket nozzle surrounding the central nozzle.In addition, 12 Nm³/h secondary air is fed into the burner chamber.

The aerosol flows out of the axial tube into the central tube. Theaerosol is a cerium salt aerosol generated by ultrasonic atomization ofa 5% aqueous cerium(III) chloride solution in the aerosol generator inan amount of 210 g/h.

The cerium salt aerosol is conducted with the aid of the carrier gas of0.5 Nm³/h air through a heated line during which the aerosol passes attemperatures of approximately 180° C. into a gas and a saline crystalaerosol.

The temperature of the gaseous mixture (SiCl₄/air/hydrogen, aerosol) is180° C. at the burner mouth.

The reaction gases and the pyrogenically produced silicic acid dopedwith cerium are drawn through a cooling system by applying a vacuum andcooled down thereby to approximately 100 to 160° C. The solid isseparated in a filter or cyclone from the gas current.

The doped, pyrogenically produced silicic acid accumulates as a white,fine powder. In a further step the adhering silicic acid remnants areremoved from the silicic acid at an elevated temperature by a treatmentwith air containing water vapor.

The BET surface of the doped, pyrogenically produced silicic acid is 143m²/g.

The production parameters are collated in table 1.

Further analytical data of the pyrogenic silicic acid obtained isindicated in table 2.

Example 2 Doping with Cerium

4.44 kg/h SiCl₄ are evaporated at approximately 130° C. and introducedinto the central tube of the burner. In addition, 3 Nm³/h primaryhydrogen and 8.7 Nm³/h air are fed into the central tube. The gaseousmixture flows out of the inner nozzle of the burner and burns into theburner chamber and the subsequent, water-cooled flame tube. In order toavoid cakings on the nozzles 0.5 Nm³/h jacket hydrogen or secondaryhydrogen is fed into the jacket nozzle surrounding the central nozzle.In addition, 12 Nm³/h secondary air is fed into the burner chamber.

The aerosol flows out of the axial tube into the central tube. Theaerosol is a cerium salt aerosol generated by ultrasonic atomization ofa 5% aqueous cerium(III) chloride solution in the aerosol generator inan amount of 205 g/h.

The cerium salt aerosol is conducted with the aid of the carrier gas of0.5 Nm³/h air through a heated line during which the aerosol passes attemperatures of approximately 180° C. into a gas and a saline crystalaerosol.

The temperature of the gaseous mixture (SiCl₄/air/hydrogen, aerosol) is180° C. at the burner mouth.

The reaction gases and the pyrogenically produced silicic acid dopedwith cerium are drawn through a cooling system by applying a vacuum andcooled down thereby to approximately 100 to 160° C. The solid isseparated in a filter or cyclone from the gas current.

The doped, pyrogenically produced silicic acid accumulates as a white,fine powder. In a further step the adhering silicic acid remnants areremoved from the pyrogenic silicic acid at an elevated temperature by atreatment with air containing water vapor.

The BET surface of the doped, pyrogenically produced silicic acid is 217m²/g.

The production parameters are collated in table 1.

Further analytical data of the pyrogenic silicic acid obtained isindicated in table 2.

Example 3 Doping with Potassium Salts

4.44 kg/h SiCl₄ are evaporated at approximately 130° C. and introducedinto the central tube of the burner. In addition, 3 Nm³/h primaryhydrogen and 8.7 Nm³/h air are fed into the central tube. The gaseousmixture flows out of the inner nozzle of the burner and burns into theburner chamber- and the subsequent, water-cooled flame tube. In order toavoid cakings on the nozzles 0.5 Nm³/h jacket hydrogen or secondaryhydrogen is fed into the jacket nozzle surrounding the central nozzle.In addition, 12 Nm³/h secondary air is fed into the burner chamber.

The aerosol flows out of the axial tube into the central tube. Theaerosol is a potassium salt aerosol generated by ultrasonic atomizationof a 0.5% aqueous potassium chloride solution in the aerosol generatorin an amount of 215 g/h.

The potassium salt aerosol is conducted with the aid of the carrier gasof 0.5 Nm³/h air through a heated line during which the aerosol passesat temperatures of approximately 180° C. into a gas and a saline crystalaerosol.

The temperature of the gaseous mixture (SiCl₄/air/hydrogen, aerosol) is180° C. at the burner mouth.

The reaction gases and the pyrogenically produced silicic acid dopedwith potassium are drawn through a cooling system by applying a vacuumand the particle gas current cooled down thereby to approximately 100 to160° C. The solid is separated in a filter or cyclone from the gascurrent.

The doped, pyrogenically produced silicic acid accumulates as a white,fine powder. In a further step the adhering silicic acid remnants areremoved from the pyrogenic silicic acid at an elevated temperature by atreatment with air containing water vapor.

The BET surface of the doped, pyrogenically produced silicic acid is 199m²/g.

The production parameters are collated in table 1.

Further analytical data of the pyrogenic silicic acid obtained isindicated in table 2.

TABLE 1 Experimental conditions in the production of doped, pyrogenicsilicic acids Primary Sec- H₂ H₂ N₂ Gas Aerosol Air SiCl₄ air air CoreJacket Jacket temp. Saline amount aerosol BET No. Kg/h Nm³/h Nm³/h Nm³/hNm³/h Nm³/h C. Solution kg/h Nm³/h m²/g 1 4.44 8.0 12 3 0.5 0.3 180 5%CeCl₃ 0.210 0.5 143 2 4.44 8.7 12 3 0.5 0.3 180 5% CeCl₃ 0.205 0.5 217 34.44 8.7 12 3 0.5 0.3 180 0.5% KCL 0.215 0.5 199 Explanation: Primaryair = amount of air in the central tube; Sec-air = secondary air;H₂-core = hydrogen in the central tube; Gas temp. = gas temperature onthe nozzle of the central tube; Aerosol amount = massive current of thesaline solution converted in aerosol form; Air aerosol = carrier gasamount (air) of the aerosol

TABLE 2 Analytical data of the specimens obtained according to examples1 to 3 CE K Cl Grindo- Sedi- pH Stamping Thickening BET wt. wt. contentTV GV Cl meter vol. 4% density in Ludopal No. (m²/g) μg/g μg/g ppm wt. %wt. % ppm μm vol. % Efficiency sus. g/l (mPas) Doping with cerium saltand reference examples 1 143 1860 <5 0.09 1.33 20 0 690 3.93 26 1990 2217 2350 <5 112 0.22 2.23 112 40 50 548 3.67 29 3680 Doping withpotassium salt and reference examples 3 199 300 55 0.32 1.86 55 60 50451 4.83 32 2575 Explanation: Cerium content as Ce in μg/g (ppm);potassium content as K in μg/g; TV = drying loss (2 h at 105° C. inaccordance with DIN/ISO 787/II, ASTM D 280, JIS K 5101/21); GV =annealing loss (2 h at 1000° C., in accordance with DIN 55921, ASTM D1208, JIS K 5101/23 relative to the substance dried 2 h at 105° C.);grindometer = grindometer value; Sedi-vol. = sediment volume; efficiency= turbulence measurement: The method of determining efficiency(turbulence measurement) is described in patent DE 44 00 170; thesuspension produced according to the same method is utilized after afurther 5 minutes waiting time to determine the sediment volume;stamping density in accordance with DIN/ISO 787/IX, JIS K 5101/18 (notsieved). Thickening in polyester reference system: Described in EP-A0,015,315.

Example 4 Production of a Pyrogenically Produced Silicic Acid Doped byAerosol with Aluminum Oxide and with a Low BET Surface

5.25 kg/h SiCl₄ are evaporated at approximately 130° C. and transferredinto central tube 2 of burner 1 of a known design. 3.47 Nm³/h (primary)hydrogen and 3.76 Nm³/h air as well as 0.95 Nm³/h oxygen areadditionally fed into central tube 2. The gaseous mixture flows out ofnozzle 3 of burner 1 and burns into the burner chamber and the adjacent,water-cooled fire tube.

0.5 Nm³/h (jacket or secondary) hydrogen and 0.3 Nm³/h nitrogen are fedinto ring nozzle 4.

20 Nm³/h (secondary) air are additionally fed into the burner chamber.

The second gas current flows out of axial tube 5 into central tube 2.

The second gas current consists of the aerosol produced by ultrasonicatomization of AlCl₃ solution in separate atomization unit 6. Aerosolgenerator 6 atomizes 460 g/h 2.29% aqueous aluminum chloride solutionthereby. The aluminum chloride aerosol is conducted with the aid of thecarrier gas of 0.5 Nm³/h air through the heated line, during which theaqueous aerosol changes at temperatures of approximately 180° C. into agas and a salt crystal.

The temperature of the gaseous mixture (SiCl₄/air/hydrogen,water/aerosol) is 180° C. at the burner mouth.

The reaction gases and the pyrogenically produced silicic acid doped byaerosol with aluminum oxide are drawn through a cooling system byapplying a vacuum. The particle gas current is cooled down thereby toapproximately 100 to 160° C. The solid is separated from the waste-gascurrent in a cyclone.

The pyrogenically produced silicic acid doped by aerosol with aluminumoxide precipitates as a white, fine powder. In a further step anystill-adhering remnants of hydrochloric acid are removed from thesilicic acid at elevated temperature by a treatment with air containingwater vapor.

The BET surface of the pyrogenic silicic acid doped by aerosol withaluminum oxide is 55 m²/g.

The production conditions are listed in table 3. Further analytical dataof the silicic acid is indicated in table 4.

Example 5

Production of a Pyrogenically Produced Silicic Acid Doped by Aerosolwith Aluminum Oxide and with a High BET Surface

4.44 kg/h SiCl₄ are evaporated at approximately 130° C. and transferredinto central tube 2 of burner 1 of a known design. 3.15 Nm³/h (primary)hydrogen and 8.2 Nm³/h air are additionally fed into central tube 2. Thegaseous mixture flows out of nozzle 3 of burner 1 and burns into theburner chamber and the adjacent, water-cooled fire tube.

0.5 Nm³/h (jacket or secondary) hydrogen and 0.3 Nm³/h nitrogen are fedinto ring nozzle 4.

12 Nm³/h (secondary) air are additionally fed into the burner chamber.

The second gas current flows out of axial tube 5 into central tube 2.

The second gas current consists of the aerosol produced by ultrasonicatomization of AlCl₃ solution in separate atomization unit 6. Aerosolgenerator 6 atomizes 450 g/h 2.29% aqueous aluminum chloride solutionthereby. The aluminum chloride aerosol is conducted with the aid of thecarrier gas of 0.5 Nm³/h air through the heated line, during which theaqueous aerosol changes at temperatures of approximately 180° C. into agas and a salt crystal.

The temperature of the gaseous mixture (SiCl₄/air/hydrogen,water/aerosol) is 180° C. at the burner mouth.

The reaction gases and the pyrogenically produced silicic acid doped byaerosol with aluminum oxide are drawn through a cooling system byapplying a vacuum. The particle gas current is cooled down thereby toapproximately 100 to 160° C. The solid is separated from the waste-gascurrent in a cyclone.

The pyrogenically produced silicic acid doped by aerosol with aluminumoxide precipitates as a white, fine powder. In a further step anystill-adhering remnants of hydrochloric acid are removed from thesilicic acid at elevated temperature by a treatment with air containingwater vapor.

The BET surface of the pyrogenic silicic acid doped by aerosol withaluminum oxide is 203 m²/g.

The production conditions are listed in table 3. Further analytical dataof the silicic acid is indicated in table 4.

TABLE 3 Experimental conditions in the production of pyrogenic silicicacid doped with aluminum oxide Primary O₂ Sec- H₂ H₂ N₂ Gas Aerosol AirSiCl₄ air Core air Core Jacket Jacket temp. Saline Amount aerosol BETNo. Kg/h Nm³/h Nm³/h Nm³/h Nm³/h Nm³/h Nm³/h C. Solution kg/h Nm³/h m²/g4 5.25 3.76 0.95 20 3.47 0.5 0.3 156 2.29% 0.46 0.5 55 aqueous AlCl₃ 54.44 8.2 0 12 3.15 0.5 0.3 180 2.29% 0.45 0.5 203 aqueous AlCl₃Explanation: Primary air = amount of air in the central tube; Sec-air =secondary air; H₂-core [nucleus] = hydrogen in the central tube; Gastemp. = gas temperature on the nozzle of the central tube; Aerosolamount = massive current of the saline solution converted in aerosolform; Air aerosol = carrier gas amount (air) of the aerosol

TABLE 4 Analytical data of the specimens obtained according to examples1 to 2-4 and 5] Stamping DBP Al₂O₃ Si₂O₃ Chloride BET PH densityabsorption content content content m²/g 4% sus. g/l g/100 g % by wt. %by wt. ppm Ex. No. 4 55 4.39 94 81 0.187 99.79 89 Ex. No. 5 203 4.15 24326 0.27 99.67 In comparison thereto Aerosil OX 50 3.8-4.8 130 160<0.08 >99.8 <250 50 Explanation: pH 4% sus. = pH of the four-percentaqueous suspension

An oxide according to example 4 is sprayed in a suitable mixingcontainer under intensive mixing, if necessary with water or dilute acidat first and subsequently with one or more or a mixture of severalsurface-modifying reagents (hydrophobing agents), subsequently mixed 15to 30 minutes, if necessary and tempered at a temperature of 100 to 400°C. for a period of 0.5-6 h. The tempering can take place underprotective gas.

The amount ratios used are listed in table 5. The characteristicphysicochemical data of the surface-modified oxides obtained are listedin table 6.

TABLE 5 H₂/O addition Tempering Tempering Hydrophobing Parts/100parts/100 time temperature Designation agent parts oxide parts oxide (h)(° C.) Example 6 Si 108 5   1 ** 2 120 Example 7 HMDS 5 1 2 140 Example8 HMDS 10 2 2 140 Example 9 PDMS 7.5 — 2 400 Example 10 AMEO 7 2 3 130 *Si 108: Octyltrimethoxysilane HMDS: Hexamethyldisilazane PDMS:Polydimethylsiloxane, here Rhodorsil 47 V 100 AMEO:γ-Aminopropyltriethoxysilane ** 0.01 n HCL was used here instead of H₂O

TABLE 6 Physicochemical data of the oxides produced BET Stamping CDrying Annealing surface density content loss loss Designation (m²/g) pH(g/l) (%) (%) (%) Example 6 46 6.4 92 2.0 0.8 2.9 Example 7 51 7.2 1040.8 0.1 0.9 Example 8 48 6.2 107 0.9 0.2 0.8 Example 9 45 7.2 104 2.00.1 2.1 Example 10 49 9.6 94 1.1 0.8 2.0

Further variations and modifications will be apparent to those skilledin the art from the foregoing and are intended to be encompassed by theclaims appended hereto. German priority application 10109484.1 is reliedon and incorporated herein by reference.

1. Surface-modified, pyrogenically produced oxides doped by aerosol. 2.Surface-modified, pyrogenically produced oxides doped by aerosol,characterized in that the oxides are oxides from the group SiO₂, Al₂O₃,TiO₂, B₂O₃, ZrO₂, In₂O₃, ZnO, Fe₂O₃, Nb₂O₅, V₂O₅, WO₃, SnO₂, GeO₂. 3.Surface-modified, pyrogenically produced oxides doped by aerosol inaccordance with claim 1 or 2, characterized in that they aresurface-modified with one or several compounds from the followinggroups: a) Organosilanes of the type (RO)₃Si(C_(n)H_(2n+1)) and(RO)₃Si(C_(n)H_(2n−1)) R alkyl n=1-20 b) Organosilanes of the typeR′_(x)(RO)_(y)Si(C_(n)H_(2n+1)) and (RO)₃Si(C_(n)H_(2n+1)) R=alkylR′=alkyl R′=cycloalkyl N=1-20 x+y=3 x=1, 2 y=1, 2 c) Halogenorganosilanes of the type X₃Si(C_(n)H_(2n+1)) and X₃Si(C_(n)H_(2n−1))X═Cl, Br n=1-20 d) Halogen organosilanes of the typeX₂(R′)Si(C_(n)H_(2n+1)) and X₂(R′)Si(C_(n)H_(2n−1)) X═Cl, Br R′=alkylR′=cycloalkyl n=1-20 e) Halogen organosilanes of the typeX(R′)₂Si(C_(n)H_(2n+1)) and X(R′)₂Si(C_(n)H_(2n−1)) X═Cl, Br R′=alkylR′=cycloalkyl n=1-20 f) Organosilanes of the type (RO)₃Si(CH₂)_(m)—R′R=alkyl m=0.1-20 R=methyl-, aryl (e.g., —C₆H₅, substituted phenylgroups) —C₄F₉, OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂ —NH₂, ═N₃, —SCN,—CH═CH₂, —NH—CH₂—CH₂—NH₂, —N—(CH₂—CH₂—CH₂NH₂)₂ —OOC(CH₃)c=CH₂—OCH₂—CH(O)CH₂ —NH—CO—N—CO— (CH₂)₅ —NH—COO—CH₃, —NH—COO—CH₂—CH₃,—NH—(CH₂)₃Si(or)₃ —S_(x)—(CH₂)₃Si(OR)₃ —SH —NR′R″R′″(R′=alkyl, aryl;R″═H, alkyl, aryl; R′″═H, alkyl, aryl, benzyl, C₂H₄NR″″R′″″ with R″″=A,alkyl and R′″″═H, alkyl g) Organosilanes of the type(R″)_(x)(RO)_(y)Si(CH₂)_(m)—R′ $\begin{matrix}{R^{''} = {alkyl}} \\{= {cycloalkyl}}\end{matrix}$ x + y = 2 x = 1, 2 y = 1, 2 m = 0.1  to  20R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups) —C₄F₉,—OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂ —NH₂, —N₃, SCN, —CH═CH₂,—NH—CH₂—CH₂—NH₂, —N—(CH₂—CH₂—NH₂)₂ —OOC(CH₃)C═CH₂ —OCH₂—CH(O)CH₂—NH—CO—N—CO—(CH₂)₅ —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃—S_(x)—(CH₂)₃Si(OR)₃ —SH —NR′R″R′″(R′=alkyl, aryl; R″═H, alkyl, aryl;R′″═H, alkyl, aryl, benzyl, C₂H₄NR″″R′″″ with R″″=A, alkyl and R′″″═H,alkyl) h) Halogen organosilanes of the type X₃Si(CH₂)_(m)—R′ X═Cl, Brm=0, 1-20 R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂ —NH₂, —N₃, SCN, —CH═CH₂,—NH—CH₂—CH₂—NH₂, —N—(CH₂—CH₂—NH₂)₂ —OOC(CH₃)C═CH₂ —OCH₂—CH(O)CH₂—NH—CO—N—CO—(CH₂)₅ —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃—S_(x)—(CH₂)₃Si(OR)₃ —SH i) Halogen organosilanes of the type(R)X₂Si(CH₂)_(m)—R′ X═Cl, Br R=alkyl such as methyl, -ethyl-, propyl-m=0, 1-20 R=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂ —NH₂, —N₃, SCN, —CH═CH₂,—NH—CH₂—CH₂—NH₂, —N—(CH₂—CH₂—NH₂)₂ —OOC(CH₃)C═CH₂ —OCH₂—CH(O)CH₂—NH—CO—N—CO—(CH₂)₅ —NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH— (CH₂)₃Si(OR)₃—S_(x)—(CH₂)₃Si(OR)₃ —SH (j) Halogen organosilanes of the type(R)₂XSi(CH₂)_(m)—R′ X═Cl, Br R=alkyl m=0, 1-20 R′=methyl-, aryl (e.g.,—C₆H₅, substituted phenyl groups) —C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃,—O—CF₂—CHF₂ —NH₂, —N₃, SCN, —CH═CH₂, —NH—CH₂—CH₂—NH₂, —N—(CH₂—CH₂—NH₂)₂—OOC(CH₃)C═CH₂ —OCH₂—CH(O)CH₂ —NH—CO—N—CO—(CH₂)₅ —NH—COO—CH₃,—NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃ —S_(x)—(CH₂)₃Si(OR)₃ —SH (k)Silazanes of the type

R=alkyl R′=alkyl, vinyl (l) Cyclic polysiloxanes of the type D 3, D 4, D5, e.g. octamethylcyclotetrasiloxane=D4

m) Polysiloxanes or silicone oils of the type

R=alkyl, aryl, (CH₂)_(n)—NH₂, H R′=alkyl, aryl, (CH₂)_(n)—NH₂, HR″=alkyl, aryl, (CH₂)_(n)—NH₂, H R′″=alkyl, aryl, (CH₂)_(n)—NH₂, H
 4. Amethod of producing the surface-modified oxides in accordance with claim1 or 2, characterized in that pyrogenically produced oxides doped byaerosol are placed in a suitable mixing container, the oxides aresprayed under intensive mixing, optionally with water and/or acid atfirst and subsequently with a surface-modification reagent or a mixtureof several surface-modification reagents, optionally re-mixed 15 to 30minutes and tempered at a temperature of 100 to 400° C. for a period of1 to 6 hours.
 5. The use of the surface-modified oxides as reinforcingfiller.